A.隔離可信任網(wǎng)絡和不可信任網(wǎng)絡 B.防止病毒和木馬程序的入侵 C.隔離內(nèi)網(wǎng)與外網(wǎng) D.監(jiān)控網(wǎng)絡中會話狀態(tài)
A.TCP B.IP C.ICMP D.UDP